Compounds of the formula: ##STR1## in which Z.sup.2 is hydrogen, methyl, or ethyl are broad spectrum antineoplastic agents. See U.S. Pat. No. 4,684,653. These compounds, of which N-(4-[2-(2-amino-4-hydroxy-5,6,7,8-tetrahydropyrido[2,3-d]pyrimidin-6-yl)e thyl]benzoyl)-L-glutamic acid is representative, have been prepared previously through a lengthy synthesis in which a 2-(protected amino)-4-hydroxy-6-[2-(4-carboxyphenyl)ethyl]pyrido[2,3-d]pyrimidine is coupled with a diester of L-glutamic acid utilizing peptide condensation techniques. The resultant dialkyl N-(4-[2-(2-protected amino-4-hydroxypyrido[2,3-d]-pyrimidin-6-yl)ethenyl]benzoyl)-L-glutamate is then hydrogenated, following which the protecting groups are removed. By reason of the ethenyl intermediate, the process is limited to the preparation of compounds having at least two carbon atoms in the bridge between the tetraydropyridine ring and the phenyl ring.